Need opinions on E3 Spark plugs.I hear the maker had used on his Isuzu Rodeo and got mileage from 17.5 to 19 mpg and more zip.

I tried them out in my Rodeo and got some added balls but the mileage dropped 15% and took them out and saw that the tips and electrodes were clean and the insulators were white..BUT the base was all black with sooty carbon.Plugs were non gappable and were torqued within specs with a dab of antiseize.

List some good things about them along with the bad and what vehicle application